G3 Leak Detection and Testing Procedures

Question 1

Which leak detection method is most commonly used for a quick field check of gas piping joints?

Accepted Answer

Soap bubble solution applied to joints

Answer

Electronic combustible gas detector

Answer

Pressure gauge monitoring over time

Answer

Ultraviolet dye injection

Question 2

Before applying pressure for a leak test on a new gas piping installation, what must a technician ensure?

Accepted Answer

All open ends are capped and appliance connections are isolated

Answer

All appliances are turned on to full capacity

Answer

The gas meter is fully open

Answer

The main shutoff valve is open

Question 3

What is the minimum test pressure typically required for a pressure integrity test on a residential gas piping system according to most North American codes?

Accepted Answer

10 psi

Answer

1.5 psi

Answer

3 psi

Answer

25 psi

Question 4

When performing a pressure drop test, a technician notices a pressure drop of 0.5 in. W.C. over 10 minutes. What does this indicate?

Accepted Answer

A leak is present in the system

Answer

The system is leak-free and passes the test

Answer

The gauge is malfunctioning

Answer

Normal thermal expansion is occurring

Question 5

Which gas has the lowest explosive limit (LEL) making leak detection especially critical?

Accepted Answer

Propane

Answer

Natural gas (methane)

Answer

Butane

Answer

All fuel gases have the same LEL

Question 6

What is the primary reason soap solutions containing chlorides should NOT be used for leak detection on stainless steel gas piping?

Accepted Answer

Chlorides cause stress corrosion cracking in stainless steel

Answer

They are too thick to reveal small leaks

Answer

They leave residue that blocks gas flow

Answer

They react with gas to form toxic compounds

Question 7

After a gas leak is detected and repaired, what must a technician do before restoring gas service?

Accepted Answer

Re-test the repaired section to confirm the leak is eliminated

Answer

Wait 24 hours for the repair to cure

Answer

Notify the gas utility immediately

Answer

Replace the entire section of pipe